Battery assembly techniques

ABSTRACT

Battery assembly techniques and a corresponding system are disclosed. In various embodiments, the battery assembly techniques include compressing battery cells and inserting the battery cells in a can. Battery cells are stacked and then compressed using pneumatic cylinders that exert pressure on a first external layer of the stacked battery cells. A first portion of the stacked battery cells is released from the pneumatic cylinders while a second portion of the battery cells remains compressed. The first portion of the stacked battery cells is inserted in a can. In various embodiments, friction decreasing materials are added to the stacked battery cells to compress the stacked battery cells or ease insertion.

CROSS REFERENCE TO OTHER APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/908,556, entitled BATTERY ASSEMBLY TECHNIQUES filed Feb. 28,2018 and is a continuation of U.S. patent application Ser. No.15/471,947, entitled BATTERY ASSEMBLY TECHNIQUES filed Mar. 28, 2017,now bearing U.S. Pat. No. 9,941,542, which claims priority to U.S.Provisional Application No. 62/395,594, entitled BATTERY SUBMODULE ANDASSEMBLY TECHNIQUES filed Sep. 16, 2016 which are incorporated herein byreference for all purposes.

BACKGROUND OF THE INVENTION

Proper battery assembly is integral to producing safe, high qualitybattery packs. Placing a plurality of pouch cells into a battery casewhile maintaining compression on the cells may be required duringbattery assembly. A method that is automated may improve upon theassembly process. Additional design features which reduce frictionbetween the plurality of pouch cells and the battery case may improveupon the assembly process.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1A is a diagram illustrating an embodiment of a battery.

FIG. 1B is a diagram illustrating an embodiment of a battery from a topview.

FIG. 2 is a diagram illustrating an embodiment of a sealed battery.

FIG. 3A is a diagram illustrating an embodiment of a battery assemblysystem.

FIG. 3B is a diagram illustrating an embodiment of a battery assemblysystem before compression.

FIG. 3C is a diagram illustrating an embodiment of a battery assemblysystem in the process of compression.

FIG. 3D is a diagram illustrating an embodiment of a removal of astacking fixture.

FIG. 3E is a diagram illustrating an embodiment of insertion in a can.

FIG. 4A is a diagram illustrating an embodiment of a battery assemblysystem before insertion in a can.

FIG. 4B is a diagram illustrating an embodiment of a battery assemblysystem during insertion in a can.

FIG. 5 is a flow diagram illustrating an embodiment of a batteryassembly process.

FIG. 6 is a diagram illustrating an embodiment of a battery comprisinglow friction cell covers.

FIG. 7 is a diagram illustrating an embodiment of a low friction band.

FIG. 8 is a diagram illustrating an embodiment of a low friction band.

FIG. 9 is a flow diagram illustrating an embodiment of a batteryassembly process.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess; an apparatus; a system; a composition of matter; a computerprogram product embodied on a computer readable storage medium; and/or aprocessor, such as a processor configured to execute instructions storedon and/or provided by a memory coupled to the processor. In thisspecification, these implementations, or any other form that theinvention may take, may be referred to as techniques. In general, theorder of the steps of disclosed processes may be altered within thescope of the invention. Unless stated otherwise, a component such as aprocessor or a memory described as being configured to perform a taskmay be implemented as a general component that is temporarily configuredto perform the task at a given time or a specific component that ismanufactured to perform the task. As used herein, the term ‘processor’refers to one or more devices, circuits, and/or processing coresconfigured to process data, such as computer program instructions.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

A battery assembly method and system are disclosed. The battery assemblymethod comprises stacking a plurality of battery cells to create a stackof battery cells and compressing the stack of battery cells. Compressingthe stack of battery cells comprises exerting pressure on a firstexternal layer of the stack of battery cells using a plurality ofpneumatic cylinders. A first portion of the stack of battery cells isreleased from the plurality of pneumatic cylinders while a secondportion of the stack of battery cells remains compressed by theplurality of pneumatic cylinders. The first portion of the stack ofbattery cells is inserted in a can. The battery cells may retaincompression while being inserted in the can. The process may repeatuntil the stack of battery cells is fully inserted in the can. Thebattery assembly system carries out the battery assembly method. In someembodiments, the stack of battery cells comprises insulation,conductors, or both in addition to cells. A plurality of pneumaticcylinders may exert pressure on a second external layer of the stack ofbattery cells.

In some embodiments, the battery assembly system enables a battery to beassembled efficiently and accurately. A battery may require compressinglayers of cells and other contents before inserting them in a fullysealed case (e.g. a can). The battery assembly system may decreasefriction and resistance typical in inserting one or more of thefollowing: battery cells, insulation, or conductors, in the can. Anapparatus comprising pneumatic cylinders may be used to compress thebattery cells. The pneumatic cylinders may allow the battery cells to beinserted portion by portion into the can, wherein portions of thebattery cells that are not near the opening of the can remain compressedby the pneumatic cylinders. In some embodiments, the battery cells arecompressed while held in a stacking fixture. The stacking fixture isremoved following compression and the battery cells are inserted in thecan. In some embodiments, pneumatic cylinders are installed onstructures that move the cylinders in a direction perpendicular to thecylinders' active direction (e.g. the direction in which the cylindersexert pressure), allowing the cylinders to drop the battery cells intothe can. In various embodiments, various configurations of frictiondecreasing materials may be used such as cell covers or bands. Bandingmay also serve to compress the cells and enable easier insertion intothe can.

FIG. 1A is a diagram illustrating an embodiment of a battery. Thebattery assembly system may be used to assemble various types ofbatteries. Battery 100 illustrates an embodiment of a battery assembledby the system. The battery as shown comprises stacked componentsenclosed in a sealed can assembly. The can may be used as a heat sinkand may comprise aluminum or any other appropriate material. The can maybe sealed to the battery pack structure. The can may comprise an openingwherein the battery cells are inserted. In some embodiments, a cover isplaced at the can's opening after the battery cells are inserted tocreate a fully sealed battery.

FIG. 1B is a diagram illustrating an embodiment of a battery from a topview. Alternating layers of the battery components are shown. Thermalrunaway propagation prevention features are built into the batterydesign.

A battery cell stack may comprise non-cell layers. Thermal insulation,conductors, and cells may be stacked in the can. Layers of cells may beplaced in between layers of insulation. Insulation layer 150 maycomprise an aerogel, fiberglass, fiberglass infused with aerogel, or anyappropriate insulating material. The insulation shown in this embodimentis a compressible material. In some embodiments, aluminum fins areplaced in between cells. The fins may provide thermal contact. Celllayer 152 may comprise a liquid electrolyte. In some embodiments, thebattery assembly system aligns the stacked layers of the battery andfits the stacked and aligned layers into the can. The components of thebattery may be required to be compressed and tightly secured in the can.

FIG. 2 is a diagram illustrating an embodiment of a sealed battery.Cover 202 is sealed to can 200. The diagram shows an embodiment of afinal assembled battery. Can 200 may comprise an impact extruded can.Cells are stacked in the can. In some embodiments, the can is made of1070 T0 aluminum. The can has 0.024″ wall thickness and 1/16″ bottomthickness. The can has a flanged top for sealing. After assembly, thecan may be compressed for proper cell compression.

The can may be plastically formed in a fixture to provide specified cellcompression (e.g., 3 PSI). The insulation may act as a spring to providea specified cell compressive force. The compression may secure the cells(e.g., no load on the tabs) and improve cell cycle life. The batteryassembly system may be required to compress the battery component stackin order to insert it into the can.

FIG. 3A is a diagram illustrating an embodiment of a battery assemblysystem. In the example shown, system 300 comprises stacking fixture 352,pneumatic cylinder 350, and pneumatic cylinder 354. Stacking fixture 352may comprise plastic, glass, polytetrafluoroethylene, polyoxymethylene,Delrin®, or any appropriate material that does not bind to a batterycase.

Various configurations of stacking fixtures may be used. The stackingfixture may be used to align or maintain alignment of the layers of thebattery during compression. As shown, stacking fixture 352 is arectangular prism shape with open panels. The stacking fixture maycomprise two parallel vertical panels. In various embodiments, thestacking fixture comprises one connected apparatus or multiple movingcomponents. The battery assembly system may comprise interchangeableparts. For example, a user may choose between various stacking fixtureconfigurations. The stacking fixture may comprise a frame or case basedon the shape of the plurality of battery cells or layers. For example,the stacking fixture may fit the dimensions of stack of battery cells.The stack of battery cells may comprise insulating or conducting layersin addition to cells.

Pneumatic cylinder 350 as shown is positioned above the battery cellsand pneumatic cylinder 354 is positioned below the battery cells. Layersof the battery (e.g. cells, insulation, or conductors) may be stacked inthe stacking fixture. The pneumatic cylinders may be used to exertpressure on the top and bottom battery layers, compressing the cells ofthe battery. In some embodiments, multiple pneumatic cylinders are usedto compress the cells from both sides. For example, multiple pneumaticcylinders may press down on the top of the cell stack while multiplepneumatic cylinders exert pressure on the bottom of the cell stack.

FIG. 3B is a diagram illustrating an embodiment of a battery assemblysystem before cell compression. In the example shown, stacking fixture312 is one piece. The shape of the stacking fixture comprises tworectangular panels that are appended to a hollow rectangular prism.Cells 310 are stacked in the stacking fixture. Cells 310 may comprisethe layers of the battery, including any non-cell layers.

The two solid side panels may be used to prevent cells or layers of thebattery from sliding out of position. The hollow rectangular prism atone end of the stacking fixture may be used to align the battery cells.In the example shown, pneumatic cylinders 302 and 306 press down uponcomponents 308 and 304 respectively. Components 308 and 304 may bedesigned to evenly press down upon the battery cells. For example, theymay be evenly spaced across the topmost layer or their lengths may beequal to the exposed width of the topmost layer of the battery cellstack. The components may be semi-permanently attached to the pneumaticcylinders. Pneumatic cylinders 314 and 316 may also similarly compactthe battery cell stack from below.

FIG. 3C is a diagram illustrating an embodiment of a battery assemblysystem in the process of battery compression. In the example shown,pneumatic cylinders 302 and 306 push down on the top layer of batterycells 310. Battery cells 310 are compressed compared to the previousposition in FIG. 3B. Pneumatic cylinders 314 and 316 have advanced thebottom layer of battery cells 310 upwards compared to the previousposition in FIG. 3B. Battery cells 310 are compacted smaller than thedimensions of stacking fixture 312. Following compression, the stackingfixture may be removed.

FIG. 3D is a diagram illustrating an embodiment of a removal of astacking fixture. Following compression, stacking fixture 312 may beremoved from its hollow rectangular prism side. The stacking fixture mayslide easily off of the compacted battery cells. As shown, stackingfixture 312 is halfway removed from battery cells 310. Pneumaticcylinders 306, 302, 314, and 316 remain in contact with and compressbattery cells 310.

FIG. 3E is a diagram illustrating an embodiment of insertion into a can.The assembly system may compress the cells of the battery into a compactshape that is able to slide into a can. The system may solve thedifficult assembly step of transferring cells from a fixture to the can.As shown, can 312 is slid on to battery cells 310. As the can isadvanced, the nearest pneumatic cylinders are retracted. In variousembodiments, the can is advanced towards the stack of battery cells orthe stack of battery cells is advanced towards the can. Other pneumaticcylinders may remain in position, compressing the battery cells, untilthe can is advanced to the pneumatic cylinders. As shown, battery cells310 are halfway inserted in can 312. Pneumatic cylinders 306 and 314 areretracted. Pneumatic cylinders 302 and 316 remain in contact with thebattery cells. In some embodiments, 6, 10, or any appropriate number ofpneumatic cylinders may be utilized.

In some embodiments, a first portion of the stacked battery cells isreleased from pneumatic cylinders prior to being inserted in the can.For example, pneumatic cylinders 306 and 314 may be released before thecan is advanced on the first portion of the stacked battery cells. Insome embodiments, a portion of the stacked battery cells is insertedprior to being released by the pneumatic cylinders. For example, can 312may be advanced up to component 304. After advancing the can, pneumaticcylinders 302 and 316 may release the portion of the stacked batterycells.

FIG. 4A is a diagram illustrating an embodiment of a battery assemblysystem before insertion in a can. A battery assembly system maysimultaneously compress the battery cells and insert them into a can. Inthe example shown, battery cells 408 are lowered into can 410. Batterycells 408 are compressed between pneumatic cylinders. Pneumaticcylinders 400, 402, and 404 are supported by structure 406 and exertpressure on one side of the battery cells. Pneumatic cylinders 412, 414,and 416 are supported by structure 418 and exert pressure on an oppositeside of the battery cells. Compressing the battery cells while insertingthem into a can may allow the battery cells to be inserted quickly orpreserve alignment of the cells.

FIG. 4B is a diagram illustrating an embodiment of a battery assemblysystem during insertion in a can. Battery cells 408 are partiallyinserted into can 410. Pneumatic cylinders 400, 402, and 404 may bemoved up and down via structure 406. In various embodiments, thestructure, the pneumatic cylinders, or both the structure and pneumaticcylinders may be repositioned to lower the battery into the can.Pneumatic cylinders 412, 414, and 416 may similarly move up and down viastructure 418. As the battery cells as lowered, pneumatic cylindersnearest the can may retract. The pneumatic cylinders may be retracted inpairs. As shown, pneumatic cylinders 404 and 416 are retracted. Theportion of the battery cells that were compressed by pneumatic cylinders404 and 416 are inserted in the can. The battery cells may be loweredone portion of the battery cells at a time. The battery cells that arenot yet in the can may remain compressed by pneumatic cylinders. Forexample, pneumatic cylinders 400, 402, 412, and 414 as shown compressbattery cells 408. The final portion of the battery cells may be firmlypushed into the can. The battery assembly system may allow the batterycells to remain actively compressed for as long as possible duringinsertion of the cells into the can.

FIG. 5 is a flow diagram illustrating an embodiment of a process forbattery assembly. In some embodiments, the compression and insertion ofthe battery cells occur simultaneously. A combination compression andinsertion apparatus may be used.

In 500, the battery cells are positioned between pneumatic cylinders. In502, the battery cells are compressed. In 504, the battery cells areinserted into a can and pneumatic cylinders near the can are retracted.For example, the pneumatic cylinders that are closest to an opening inthe can may be retracted. In 506, it is determined whether the batterycells are fully inserted into the can. In the event the battery cellsare determined to be fully inserted into the can, in 508 the can issealed. Sealing the can may comprise inserting a top plate comprising athermistor, cell interconnects, or latches. A tab cover may be sealedover the top plate using an adhesive or solvent bond. Following 508, theprocess is finished. In the event the battery cells are determined to benot fully inserted into the can, the process returns to 504.

FIG. 6 is a diagram illustrating an embodiment of a battery comprisinglow friction cell covers. The battery may comprise components thatenable the battery to be assembled efficiently. In some embodiments, thebattery cell stack may bind to the can or create friction as it isinserted. For example, insulating layers made with aerogel (e.g.fiberglass infused with aerogel) may be binding, causing uneveninsertion into the can. Low friction cell covers may allow the batterycells to slide easily into a can. Low friction cell covers may be placedas the first and final layers of the battery cell stack. The lowfriction cell covers may comprise a slippery material, such as aplastic, polytetrafluoroethylene, polyoxymethylene, Delrin®, or anyother appropriate material. The low friction cell cover may compriseinsulating properties to prevent melting or fire. For example, the lowfriction cell cover may comprise a slick material with an insulatingcoating such as intumescent paint. Intumescent materials may provideenergy absorption due to phase change. Intumescent paint or additivesmay be used. As shown, low friction cell covers 600 and 602 are placedon either end of the stacked battery cells.

FIG. 7 is a diagram illustrating an embodiment of a low friction band. Alow friction band may compress a battery cell stack and allow it to beinserted into a can smoothly. In the example shown, low friction band207 is wrapped around battery cells 700. Low friction band 207 maycomprise a low friction material such as a plastic,polytetrafluoroethylene, polyoxymethylene, Delrin®, or any appropriatematerial. The low friction material may be coated in an insulatingmaterial such as intumescent paint. In some embodiments, the lowfriction band compresses the battery cell stack. The low friction mayband may enable the battery cells to maintain compression and also slideeasily into the can. The low friction band or low friction cell coversmay be applied manually or automatically to the battery cells. Forexample, an off the shelf banding machine may be used.

FIG. 8 is a diagram illustrating an embodiment of a low friction band.As shown, low friction band 802 is wrapped around battery cells 800. Thelow friction band as shown is wrapped vertically around the batterycells. In some embodiments, wrapping the band vertically allows metalfins on either side of the battery layers to efficiently disperse heatfrom the battery. Wrapping the band vertically may also allow additionallow friction material to be present on the first and last stacks of theband compared to wrapping the band horizontally around the batterycells. In some embodiments, a low friction band is an extension of lowfriction cell covers. For example, the low friction cell covers maycontinue to loop around the entire stack of battery cells.

FIG. 9 is a flow diagram illustrating an embodiment of a batteryassembly process. In 900, the battery cells are stacked. In 902, a lowfriction band or cell covers are applied. Various friction decreasingcomponents may be used separately or in combination. For example, ahorizontal low friction band may be used in addition to low frictioncell covers. In 904, the battery cells are compressed. In someembodiments, the battery cells are compressed using a low friction band.In some embodiments, an apparatus dedicated to compression is used. In906, the battery cells are inserted into a can. In 908, the can issealed.

In some embodiments, a low friction decreasing component is removedafter battery cells are inserted in the can. For example, low frictioncell covers may be removed from the can after battery cells are insertedin the can.

In various embodiments, a friction decreasing component and assemblyapparatus are used in combination or separately. For example, a batterycell stack may be compressed and inserted into a can solely using a lowfriction band. A battery cell stack may be compressed using a stackingfixture and inserted into a can without extra friction decreasingmeasures. Following compression using the apparatus of FIG. 3B, thecompressed battery cells may be sealed with a band. The battery cellsmay then be removed from the pneumatic cylinders and inserted in a can.

In some embodiments, the battery assembly system is automated. Thesystem may comprise an interface and processor. Desired specificationssuch as compression level, number of pneumatic cylinders used, spacingof pneumatic cylinders, speed of assembly, or any other appropriatefactor may be provided to the system via the interface. For example, theuser may specify how fast the battery is dropped or how fast thepneumatic cylinders are retracted. Stacking the battery cells, insertingthe battery cells into a can, and/or sealing the can may be automated.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

What is claimed is:
 1. A battery assembly system comprising: a stackingfixture configured to stack a plurality of battery cells to create astack of battery cells; and a first set of pneumatic cylindersconfigured to compress the stack of battery cells by exerting pressureon an external layer of the stack of battery cells while the stack ofbattery cells is in the stacking fixture, wherein the first set ofpneumatic cylinders are configured to be retracted one by one after thecompressed stack of battery cells is removed from the stacking fixtureand while the compressed stack of battery cells is inserted into a bin,the first set of pneumatic cylinders including: a first pneumaticcylinder compressing a first portion of the stack of battery cells; anda second pneumatic cylinder compressing a second portion of the stack ofbattery cells, the first pneumatic cylinder configured to be retractedfrom the first portion of the stack of battery cells while the secondpneumatic cylinder still compresses the second portion of the stack ofbattery cells outside the bin.
 2. The battery assembly system of claim1, wherein the stack of battery cells comprises insulation, conductors,or both insulation and conductors.
 3. The battery assembly system ofclaim 1, wherein the battery assembly system is configured to seal thebin after the stack of battery cells is fully inserted in the bin. 4.The battery assembly system of claim 1, further comprising: a second setof pneumatic cylinders configured to exert pressure on an additionalexternal layer of the stack of battery cells, compressing the stack ofbattery cells.
 5. The battery assembly system of claim 4, wherein adirection of the pressure exerted by the second set of pneumaticcylinders is opposite to a direction of the pressure exerted by thefirst set of pneumatic cylinders.
 6. The battery assembly system ofclaim 1, wherein the stacking fixture is further configured to maintainan alignment of the plurality of battery cells.
 7. The battery assemblysystem of claim 1, wherein the stacking fixture comprises a frame basedon a shape of the plurality of battery cells.
 8. The battery assemblysystem of claim 1, wherein the battery assembly system is configured toadd a cell cover or band comprising a low friction material to the stackof battery cells prior to inserting the stack of battery cells in thebin.
 9. The battery assembly system of claim 8, wherein the batteryassembly system is further configured to remove the cell cover or bandfollowing insertion of the stack of battery cells in the bin.
 10. Thebattery assembly system of claim 8, wherein the low friction material iscoated in an insulating material.
 11. The battery assembly system ofclaim 8, wherein the band compresses the stack of battery cells.
 12. Thebattery assembly system of claim 1, wherein the stacking fixturecomprises a rectangular prism with one or more open panels.
 13. Thebattery assembly system of claim 1, wherein the stacking fixturecomprises two rectangular panels appended to a hollow rectangular prism.14. The battery assembly system of claim 1, further comprising: asupporting structure coupled to the first set of pneumatic cylindersconfigured to support the first set of pneumatic cylinders.
 15. Thebattery assembly system of claim 1, wherein the stacking fixturecomprises at least one open panel, wherein the first set of pneumaticcylinders are configured to compress the stack of battery cells byexerting pressure on the external layer of the stack of battery cellsthrough the at least one open panel of the stacking fixture.
 16. Abattery assembly system comprising: a stacking fixture configured tostack a plurality of battery cells to create a stack of battery cells,wherein the stacking fixture comprises a rectangular prism with one ormore open panels; and a first set of pneumatic cylinders configured tocompress the stack of battery cells by exerting pressure on an externallayer of the stack of battery cells while the stack of battery cells isin the stacking fixture, wherein the first set of pneumatic cylindersare configured to be retracted one by one while the compressed stack ofbattery cells is removed from the stacking fixture and inserted into abin, the first set of pneumatic cylinders including: a first pneumaticcylinder compressing a first portion of the stack of battery cells; anda second pneumatic cylinder compressing a second portion of the stack ofbattery cells, the first pneumatic cylinder configured to be retractedfrom the first portion of the stack of battery cells while the secondpneumatic cylinder still compresses the second portion of the stack ofbattery cells outside the bin.